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b=tUO0xHo2KuV3/ggS9q3Czj438plTKhE6leYB2ZDQ6RnvehfVEqAycGFkjsVY5KPQo dfjULAKePyXHeJnlxYeyrExiDx+JpnttyuJpx3lh/EqsS2SuxaZXYaWuh6YZadCQDg RxcF77MOnziDHzPIrht/ah2AkvONnWj0uC5kSp/fJDzKVbo144tDPMht4yTuxnntHP ZRskTutXLbyylrxryB4WEtSRAqFEJOnaF2j9Y6mWBEahgGULlZG1zCXdPOXpF2tQHf GRx8MCYq3S3bbtYFRGxukF5x7nAdJX59i5w+vNxCT7Os+2vVPsACNEITEHjJmK6EAC ocXCPvJoM73NA== Message-ID: Date: Mon, 11 May 2026 15:46:14 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 08/22] mm: introduce for_each_free_list() Content-Language: en-US To: Brendan Jackman , Borislav Petkov , Dave Hansen , Peter Zijlstra , Andrew Morton , David Hildenbrand , Wei Xu , Johannes Weiner , Zi Yan , Lorenzo Stoakes Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, rppt@kernel.org, Sumit Garg , derkling@google.com, reijiw@google.com, Will Deacon , rientjes@google.com, "Kalyazin, Nikita" , patrick.roy@linux.dev, "Itazuri, Takahiro" , Andy Lutomirski , David Kaplan , Thomas Gleixner , Yosry Ahmed References: <20260320-page_alloc-unmapped-v2-0-28bf1bd54f41@google.com> <20260320-page_alloc-unmapped-v2-8-28bf1bd54f41@google.com> From: "Vlastimil Babka (SUSE)" In-Reply-To: <20260320-page_alloc-unmapped-v2-8-28bf1bd54f41@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 8B40340009 X-Rspam-User: X-Stat-Signature: j1o5xepzy5xce1joyh7sbai8x5u4i4me X-HE-Tag: 1778507182-283810 X-HE-Meta: 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 SPZXbaN/ OC8T62nQd078eq+97fFgeCHEVbj0ymz9pvukL0ef1HwnBKOoBNVm+UjAPc1GAqnxpq7I/l6FUqllMSnb86jbroJoMaQMuI6Pa5kdMJY9SBcYrBhAzRzc26fTBpQfa6ExooWpZUI/XFPUmx1KSX7eMEUDtvsFQY3PqI0zw1mWayEVWjKRGwlRKsUpeLmfO+txPfr6qhXF7V1vUDlrBddXkmGw0xUxrd9A3rJGQN+UOlq2NOZ0vfNkDROjQ9pPbecmDRYlQ6K5/vIjJsOoUV3vtYQ7tAwC/HlqWkXwO0AQCjqYKR7CSMNtR5i3lyA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/20/26 19:23, Brendan Jackman wrote: > Later patches will rearrange the free areas, but there are a couple of > places that iterate over them with the assumption that they have the > current structure. > > It seems ideally, code outside of mm should not be directly aware of > struct free_area in the first place, but that awareness seems relatively > harmless so just make the minimal change. I think we should lift the code from kernel/power/snapshot.c to under mm/ eventually, ISTR discussing it somewhere recently. But doesn't have to be in this series. > Now instead of letting users manually iterate over the free lists, just > provide a macro to do that. Then adopt that macro in a couple of places. > > Signed-off-by: Brendan Jackman Reviewed-by: Vlastimil Babka (SUSE) > --- > include/linux/mmzone.h | 7 +++++-- > kernel/power/snapshot.c | 8 ++++---- > mm/mm_init.c | 11 +++++++---- > 3 files changed, 16 insertions(+), 10 deletions(-) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index 7bd0134c241ce..c49e3cdf4f6bb 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -177,9 +177,12 @@ static inline bool migratetype_is_mergeable(int mt) > return mt < MIGRATE_PCPTYPES; > } > > -#define for_each_migratetype_order(order, type) \ > +#define for_each_free_list(list, zone, order) \ > for (order = 0; order < NR_PAGE_ORDERS; order++) \ > - for (type = 0; type < MIGRATE_TYPES; type++) > + for (unsigned int type = 0; \ > + list = &zone->free_area[order].free_list[type], \ > + type < MIGRATE_TYPES; \ > + type++) \ > > extern int page_group_by_mobility_disabled; > > diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c > index 7dcccf378cc2f..abd33ca13eec4 100644 > --- a/kernel/power/snapshot.c > +++ b/kernel/power/snapshot.c > @@ -1245,8 +1245,9 @@ unsigned int snapshot_additional_pages(struct zone *zone) > static void mark_free_pages(struct zone *zone) > { > unsigned long pfn, max_zone_pfn, page_count = WD_PAGE_COUNT; > + struct list_head *free_list; > unsigned long flags; > - unsigned int order, t; > + unsigned int order; > struct page *page; > > if (zone_is_empty(zone)) > @@ -1270,9 +1271,8 @@ static void mark_free_pages(struct zone *zone) > swsusp_unset_page_free(page); > } > > - for_each_migratetype_order(order, t) { > - list_for_each_entry(page, > - &zone->free_area[order].free_list[t], buddy_list) { > + for_each_free_list(free_list, zone, order) { > + list_for_each_entry(page, free_list, buddy_list) { > unsigned long i; > > pfn = page_to_pfn(page); > diff --git a/mm/mm_init.c b/mm/mm_init.c > index 969048f9b320c..f6f9455bc42b6 100644 > --- a/mm/mm_init.c > +++ b/mm/mm_init.c > @@ -1445,11 +1445,14 @@ static void __meminit zone_init_internals(struct zone *zone, enum zone_type idx, > > static void __meminit zone_init_free_lists(struct zone *zone) > { > - unsigned int order, t; > - for_each_migratetype_order(order, t) { > - INIT_LIST_HEAD(&zone->free_area[order].free_list[t]); > + struct list_head *list; > + unsigned int order; > + > + for_each_free_list(list, zone, order) > + INIT_LIST_HEAD(list); > + > + for (order = 0; order < NR_PAGE_ORDERS; order++) > zone->free_area[order].nr_free = 0; > - } > > #ifdef CONFIG_UNACCEPTED_MEMORY > INIT_LIST_HEAD(&zone->unaccepted_pages); >